TICK
BITES

In this column we will look at tick bites, focusing on Rocky
Mountain spotted fever and Lyme disease. These are diseases that
are transmitted to humans when they are bitten by an infected
tick. Ticks go through a complicated life cycle beginning as
an immature larval stage progressing to an adult phase. They
depend on blood meals to move through each stage. If a tick ingests
a microorganism at any one of it's blood meals it can pass it
on to it's next host. This is where we come in. Hunters are at
high risk because we spend a lot of time in the woods. When the
tick bites you it can transmit microorganisms into your system.
These microorganisms are the cause of our troubles. This is important
to understand. Not all tick bites cause disease because not all
ticks are infected. This has led to some controversy as to which
tick bites should be treated with antibiotics. It really depends
on what part of the country you were bitten in and what percentage
of ticks are infected. So, a tick bite in Vermont carries a lesser
risk than a bite in Pennsylvania and should be treated as such.
We will now look at the two most prevalent tick borne illnesses
and how to treat them.

Rocky Mountain Spotted Fever
I bet you thought that Rocky Mountain spotted fever describes
how you feel when a big bull sees you at 8 yards as you come
to full draw. You would think that with a name like Rocky Mountain
spotted fever this would be a disease that only western elk hunters
would have to worry about but unfortunately this is not true.
The disease is seen throughout most of the US and is very common
in areas of the southeast such as Virginia and North Carolina.
The midwest is not spared and Oklahoma and Kansas also have high
rates of disease. The microorganism that causes Rocky Mountain
Spotted fever is named Rickettsia rickettsii. The tick
carrier varies depending on what part of the country you live
in. In the west the wood tick is the carrier and in the southeast
the dog tick is the major culprit.

Rocky Mountain spotted fever produces a serious infection which
typically presents 5 -7 days after the tick bite. Fever, swelling
and rash are the symptoms which should suggest Rocky Mountain
spotted fever. The rash starts on the wrists, palms, ankles or
soles of the feet. Unfortunately the rash is not always present
in the early stages of the disease. The fever can be quite high
reaching 103 to 104F. The swelling (medically called edema) is
due to damaged leaky blood vessels from the infection and occurs
throughout your body.

Other symptoms include severe headache, lethargy, and joint pains.
Unfortunately, there are no good early tests to diagnose Rocky
Mountain spotted fever. The blood test doesn't become positive
until you have had the disease for 2-3 weeks which is too late
for early treatment. The symptoms are not specific to this disease
and without a history of a tick bite the early diagnosis can
be difficult. You hog hunters in the southeast need to tell your
physicians that you have been out playing in the woods and could
have been bitten by a tick!

The treatment for Rocky Mountain spotted fever is doxycycline
or tetracycline. The earlier the antibiotic is started the better
the chance for full recovery. At this time, prophylactic treatment
after tick bite or removal is not recommended because this changes
how the disease presents and could make the microorganisms resistant
to antibiotics. If you remove a tick or note a tick bite and
develop a fever, rash or the other symptoms we talked about,
then you should let your physician know about the bite and then
be treated with antibiotics.

Lyme Disease
Lyme disease is transmitted by Deer ticks and initially was identified
around Lyme Connecticut. The microorganism which causes Lyme
disease is Borrelai burgdorferi. In the early 1980's the
cases were mainly clustered in the Northeast but now Lyme disease
has been reported in 43 states. The incidence varies widely from
state to state and even within different counties. Most studies
on tick bites indicate that the tick requires 24-48 hours of
attachment to transmit the infection. This is probably true in
the vast majority of cases although disease transmission has
been documented with as little as 6 hours of attachment. In areas
with a high incidence of infected ticks only 1-3 % of people
with a known tick bite develop Lyme disease. The risk of disease
clearly increases with the duration of attachment. Unfortunately,
many people who develop Lyme disease don't remember a tick bite.

Once you are infected, Lyme disease is divided into 3 stages.
The initial stage is a rash called Erythema migrans which typically
appears 7-10 days after the tick bite. The rash looks like a
bullseye and occurs at or near the site of the bite. About half
the people who develop the rash will also have a flu like illness
with fever, joint pains and a headache. Untreated, the rash will
disappear in about 2 weeks but you still carry the infection.
The second stage of the disease develops 4-6 weeks after the
tick bite and is characterized by involvement of your heart and
brain. Between 5-10% of infected people will have cardiac symptoms
including irregular heartbeats or infection within the heart
muscle. Luckily, heart involvement is self limited and usually
resolves spontaneously. Nervous system involvement can develop
in up to 40% of untreated individuals. Infection can involve
both the brain(meningitis) and the peripheral nervous system
(nerves coming off your spinal cord). Symptoms can include a
severe headache, stiff neck, fever, facial droop or pain and
numbness in an extremity. These symptoms also will resolve after
5-6 months if untreated, but improve more quickly with antibiotics.
Arthritis marks the final stage of the disease. The knee is the
most commonly involved joint although others are possible. The
episodes of arthritis will last about a week but recurrences
are common. About 10% of people will have long term arthritis.
Many people at this stage also describe a constant feeling of
fatigue and short term memory loss.

Treatment of Lyme disease is somewhat controversial. As with
most medical problems we will discuss, prevention is much better
than treatment. Permethrin treated clothing and DEET can help
prevent bites. Since duration of the bite increases the risk
of transmission, daily inspection and tick removal can go a long
way toward decreasing the risk of disease. When
removing the tick it should be grasped as close to the skin as
possible with tweezers and removed with slow steady traction.
The tick's body should not be squeezed as it might inject infectious
material into your skin. Similarly, methods such as gasoline,
kerosene, or a lighted match are not recommended. These methods
typically will cause the tick to regurgitate infectious material
into your skin as it dies. Treatment of an asymptotic tick bite
depends on where you live and the duration of exposure. If you
have the tick, bring it to your physician as only deer ticks
carry Lyme disease. In most areas of the country, prophylactic
treatment is not recommended. This decision can be discussed
with your doctor. If you develop the characteristic rash, treatment
is successful with a wide variety of agents including amoxicillin
and doxycycline. For the more advanced stages of the disease
a blood test can help make the diagnosis. This test is often
negative in the early stages of the disease but should be positive
by the time symptoms beyond the rash develop. Treatment at these
stages involves more potent antibiotics at higher dosages and
for longer courses. Luckily most cases are responsive to antibiotics
and good recovery is the rule. For more information on tick borne
diseases the American Lyme Disease Foundation has an excellent
website at www.aldf.com